1. Technical Field
The present invention relates to a sofa seat device, and more particularly to a mechanical stretching device of a multifunctional convertible sofa where a leg rest may be folded or unfolded, and an angle of a back may be adjusted.
2. Related Art
A current mechanical stretching device of a convertible sofa has five major defects: 1) a seat is generally high, so that during use by a user, feet do not touch the ground, which incurs feeling of fatigue to leg portions after a period of time, thereby affecting comfort of the sofa; 2) the seat, a back, and armrests are generally high, so that a developed functional sofa is too big, and therefore not in harmony with a home environment, thereby affecting development of appearance and use of the functional sofa; 3) the seat is high, so that application of a bottom connecting rod is inflexible, and the problem that the bottom connecting rod is exposed is incurred, thereby affecting the aesthetics of the appearance of the sofa, and lowering the grade of the sofa; 4) the seat is high, so that a cushion of the sofa is thin, thereby affecting comfort of the sofa; 5) the seat is high, and cannot be applied to a classic sofa with armrests touching the ground.